The effect of pressure on the optical properties of 2H and 4H SnS2

A study is presented of the optical absorption edge of 2H-SnS2 and 4H-SnS2 at 77K and 273K and as a function of hydrostatic pressure. The results are interpreted to show that for both polytypes the lowest energy optical transition is an indirect one (Eg) and that the first direct transition (Eo) follows closely to higher energies. The results show that polytypism is significant in determining both the magnitude of the energy gaps and their pressure coefficients. This suggests that layer-layer interactions are very important for the electron states responsible for the band gaps.

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